A pusher blade such as is used in a transfer mechanism of a blood analyzer normally has an edge or portion thereof that engages test elements to push them from location A to location B. As such, a single blade has limited capability for moving such an element. The result is that if the test element has to be moved to yet other locations, locations C and/or D, some other mechanism or moving agent besides that pusher blade, must be employed. Examples of such a construction are shown in U.S. Pat. No. 4,244,032, FIG. 5, and in U.S. Pat. No. 4,302,420. U.S. Pat. No. 4,269,803 teaches a shuttle block 52 used to carry a test element from its position at station 20, left there by pusher blade 31, through more than 2 stations. That is, shuttle 52 has two pivoted, engaging surfaces or fingers 60 at the front and rear of the shuttle that project through support 25. Using the rear finger, the shuttle is able to take a test element from a "first" position at station 20, FIG. 3a, to a "second" position at station 27, FIG. 3b. When shuttle 50 is reciprocated back, and then forward again, the other, forward finger then pushes that same test element to a "third" location which is the eject station adjacent bin 66, FIG. 3c.
Thus, the aforesaid shuttle 50 comprises a moving element able to move test elements to more than two locations. However, for every location beyond two, it requires an extra upwardly projecting pivoted finger. Such a construction renders the shuttle block considerably more complicated than a simple pusher blade, and thus more expensive to manufacture. Furthermore, it is a well-established principle that the more complicated a mechanism becomes, the more likely it is that something will go wrong with it.
Therefore, there has been a need prior to this invention, to provide a less expensive form of moving element which nevertheless will move a test element through three and even four stations or locations, without necessitating the use of some other moving part.
There is an additional need to provide apparatus that is useful in environments having less than the Earth's gravity. For example, space stations have a need for blood analyzers that can operate in zero gravity.